Floating blanket



H. D. WADE ETAL 3,049,261

FLOATING BLANKET Aug. 14, 1962 2 Sheets-Sheet 1 Filed May 22, 1959 HARRY "WEE"? ALBERT E. $8.1m

Aug. 14, 1962 Filed May 22, 1959 H- D. WADE ET A].

FLOATING BLANKET 2 Sheets-Sheet 2 FIG. 6

. INVENTORS. HARRY D. WADE a ALBERT ascnslam Unite State Pate 3,049,261 FLOATING BLANKET Harry D. Wade, Cleveland, and Albert E. Seheible, Bay Village, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio Filed May 22, 1959, Ser. No. 815,118 1 Claim. (Cl. 220-26) This invention relates to an article of manufacture adapted to float on a volatile liquid, such as gasoline, to minimize the evaporation thereof. These articles are often referred to as floating blankets and will be referred to as such hereinafter.

A blanket of the type to be described herein is generally made of some flexible material, such as a plastic, that is insoluble in the volatile liquid. It contains gas pockets or gas cells so that its over-all density is less than that of the volatile liquid so that it will float on the liquid.

The use of such a blanket to prevent evaporation is accompanied by several problems. One problem is occasioned by the fact that it is commonly used on liquids in tanks, and it is usually not feasible to dismantle the tank so that the blanket can be placed on top of the liquid; however, most tanks have a man-hole through which a blanket could be inserted if the structure of the blanket permitted this. Therefore, if the blanket is flexible enough so that it can be rolled up like a pancake is rolled up to make a crepe suzette, it can be pushed through the man-hole while in this rolled-up form. The blanket will then fall down on the surface of the liquid and hopefully will unroll and cover the liquid. The design of a blanket having these properties is difficult. If the blanket is flexible enough so that it can be rolled up, it may be so flexible that it will not unroll by itself and cover the liquid, and if it is sufliciently rigid or stiff so as to be certain that it will unroll and lie flat on the liquid, it may not be possible to roll it up tightly enough for insertion through the man-hole.

Another difficulty is occasioned by the fact that the liquid in such a tank is usually pumped into and out of the tank with considerable force so that there is often great turbulence in the liquid within the tank. This sometimes causes an edge of the blanket to be folded or flipped back on itself and if the blanket is not rigid enough to resume its original flat position, it will leave a portion of the liquid exposed for evaporaion and thus defeat the purpose of the blanket.

Furthermore, even if the blanket has perfect properties when it is installed, it may lose some of its rigidity with age so that it is more easily folded back on itself as a result of the turbulence of the liquid in the tank.

It is an object of our invention to provide a floating blanket that is sufliciently flexible to be rolled up and inserted through a man-hole in a tank, and after insertion can be made sufficiently rigid so as to assure that it will lie flat as it floats on the surface of the liquid throughout its service life.

The manner in which this is accomplished can be ascertained from the following description taken in connection with the drawings forming a part hereof and in which:

FIGURE 1 is a schematic view from the top and a side with a portion cut away showing a tank with a blanket floating thereon, and in dotted lines, a blanket rolled up and being inserted through the man-hole in the tank;

FIGURE 2 is a sectional view taken on line 2-2 of FIGURE 1, looking in the direction of the arrows;

FIGURE 3 is a sectional view similar to FIGURE 2 but of an enlarged portion to show details;

FIGURE 4 is a sectional view taken on line 44 of FIGURE 2, looking in the direction of the arrows;

a a a a FIGURE 5 is a sectional view taken on line 55 of FIGURE 2, looking in the direction of the arrows;

FIGURE 6 is a sectional view showing a modified form of the stiffening means;

FIGURE 7 is a perspective view of a section of the light weight material incorporated in the blanket and causing it to float;

FIGURE 8 is a perspective view of the blanket rolled up ready for insertion through the man-hole of the tank;

FIGURE 9 is a plan view of the blanket showing an alternative form of the stiffening means;

FIGURE 10 is a plan view of the blanket showing still another alternative form of the stiffening means.

Referring now to the drawings, a tank 1 is shown generally in FIGURE 1, having a cylindrical wall 2 with a roof or cover 3 in which is formed a rim 4 defining a manhole 5. The man-hole is normally covered with a plate (not shown). The blanket of the invention is shown generally at 10, floating on the top of the liquid 11. The blanket is normally flat, as shown in full lines in FIGURE 1, but is flexible and can be rolled up, as shown at 10(a) in FIGURE 8 and in dotted lines in FIGURE 1.

The tank shown in the drawing is circular in crosssection and the blanket has an area conforming generally to the cross-sectional area of the tank. It is obvious that tanks could have other shapes and the blanket could be shaped to conform, but generally, tanks of circular cross-section provide maximum volume for a minimum amount of construction material and they are the most common.

The blanket with which the stiffening means of the invention is used may be formed of any material and have any structure which is flexible and can be rolled up as shown in FIGURE 8, but which has an over-all density less than the density of the liquid upon which it floats. In the embodiment shown, the blanket comprises two sheets 20 and 21 formed of a plastic that is insoluble in and relatively inert to the liquid. In the case of gasoline, this may be polyvinyl chloride. Those skilled in the art will be able to select plastic sheet material that is insoluble in the liquid depending upon the liquid to be protected.

Between these sheets are inserted a plurality of pieshaped pieces of foamed flexible plastic 23 such as foamed styrene or any other foamed plastic. Preferably, the foamed plastic is also insoluble in the liquid, and preferably, it is also of the closed-cell type so that if there is a rupture in the covering sheets 20 and 21 the foamed plastic will not dissolve or absorb the liquid. A pieshaped piece of the foamed plastic is shown in FIGURE 7 and a plurality of these pie-shaped pieces are placed between the sheets 20 and 21 so as to leave a small space between the individual pieces. The sheets are then heatsealed or welded around the periphery 22 and along radial lines 24 between the pie-shaped foamed pieces.

The diameter of the sheets 20 and 21 may be slightly greater than the inside diameter of the tank so that the ends of the sheet turn up slightly, as shown at 25, thus assuring that the edge of the blanket is kept in contac' with the inner wall of the tank and thus minimize evapo ration around the periphery.

In addition, a series of hollow grommets 26 forming holes, may be included in the blanket for the purpose 0: re-enforcing the two sheets and also providing small hole: through which any liquid on the surface of 'the blanke can drain back to join the liquid below the blanket. Th1 holes are small enough so that they do not significantl affect the evaporation.

The sheet material 20 and 21 and the foamed plastil 23 is sufliciently flexible so that the blanket may be roller up, as shown in FIGURE 8, and inserted through a man hole 5, as shown in FIGURE 1.

Blankets having the structure described heretofore are believed to be known in the art.

In accordance with our invention, a tubular sleeve 30 is secured to one face of the blanket by means of heatsealing or welding or by means of a flexible adhesive 31. The sleeve is also flexible and is preferablyformed of the same plastic as that used in the sheets 20 and 21. The sleeve does not interfere with the ability to roll up the blanket, as shown in FIGURE 8.

The sleeves 30 are secured around the edge of the upper face of the blanket but spaced a short distance from the periphery as shown in the drawings. While one sleeve may be employed, there are preferably at least two, as shown in FIGURE 2, but there may be three or four, as shown in FIGURES 9 and 10, respectively. The ends of the sleeves are spaced apart so as to leave a space 40 between their ends.

The sleeves are adapted to receive an elongated rod 41, as shown in FIGURES 4 and 5, or a tube 42, as shown in FIGURE 6, which may be pushed into the sleeves. The rod has the approximate length of the sleeve and is flexible enough to bend in arcuate fashion to follow the curvature of the sleeve but otherwise is relatively stifi and rigid. Alternatively, the rods or tubes :an be relatively inflexible and can be pre-shaped so as have the desired curvature. The rod or tube can be of netal or plastic or any other suitable material of the above-described physical characteristics.

At one point on the periphery of the blanket is a loop 50 shown generally in FIGURE 1 and in detail in FIG- URE 5. A cord 51 can be secured to the loop 50 and he other end of the cord can extend through the manrole to the outside of the tank as shown in FIGURE 1.

We will now describe how our blanket can be installed 11 the tank and used.

One end of the cord 51 is secured to the loop 50 and he blanket with the sleeves 30 is then rolled up as shown n FIGURE 8 with the other end of the cord extending )utside the rolled-up blanket. The blanket in the rolledip form is then pushed through the man-hole of the tank While the end of the cord 51 is held outside. The blanket will generally unroll and spread out over the surface of he liquid but if it doesnt, this is immaterial.

By means of the cord, the edge of the blanket can Je raised and held and manipulated by a mans arms exending into the man-hole. The blanket is then moved mtil one of the spaces.40 is immediately below the manhole and while the blanket is held up close to the manhole, the rod or tube 41 or 42 is pushed into the sleeve. The rod or tube is inserted in each sleeve 30 and the blanket is then permitted to fall down on the liquid. The end of the cord 51 is generally fastened outside the tank so that it can be used to raise an edge of the blanket for inspection during its service, if this seems to be desirable.

As a result of having the stifiening member follow sub- Stantially the entire periphery of the blanket, there is no possibility of an edge of the blanket bending or folding back itself after the stiffening members have been inserted in the sleeves.

Having described our invention and the best mode we contemplate for carrying it out, we particularly point out and distinctly claim the subject matter of our invention as follows.

We claim:

A device comprising a liquid storage tank having a man-hole therein, an evaporation-inhibiting blanket having a peripheral portion positioned within said tank and being sufliciently buoyant to float on liquid in the tank, the size and shape of said blanket substantially conforming to the horizontal cross-sectional area of the tank, said blanket having a plurality of peripherally arranged arouate sleeves extending substantially completely around said peripheral portion, a stifiening member slidably mounted within each of said sleeves and completely housed therein, said blanket being formed of sufliciently thin and sufficiently flexible material to permit the blanket to be rolled into an elongated substantially cylindrical package having a transverse cross-section smaller than the transverse cross-section of said man-hole to enable passage therethrough, grappling means aflixed to said blanket to enable manipulation thereof from outside of the man-hole in the tank to facilitate insertion of the stifiening members into said sleeves after said blanket has been inserted through said man-hole.

References Cited in the file of this patent UNITED STATES PATENTS 2,330,366 Jayne Sept. 28, 1943 2,847,142. McClintock etal Aug. 12, 1958 2,867,346 Champagnat Jan. 6, 1959 2,867,347 Champagnat Jan. 6, 1959 2,873,042 Fino Feb. 10, 1959. 

